The investigations of unsteady effects and its direct impact on heat transfer enhancement is the main subject of the work. Vortex structures and heat transfer mechanism in a turbulent flow over a single dimple and a staggered dimple array in a narrow channel have been investigated using Large Eddy Simulation (LES), Reynolds-averaged Navier-Stokes (RANS) simulation, POD method, Laser Doppler Velocimetry (LDV), time resolved pressure measurements and dye visualizations. Further a multi-objective design optimization has been performed for further improvement of the heat exchanger performance.
